Photosensitive or photopolymerizable compositions typically include, for example, an ethylenic unsaturated bond-containing polymerizable compound and a photopolymerization initiator. Such photosensitive or photopolymerizable compositions polymerize and cure when irradiated with light, and are therefore used, for example, in photosetting or photocuring inks, photosensitive printing plates, color filter resists, black matrix resins, and a variety of photoresists, including dry film resists.
In recent years, demand has arisen for photosensitive or photopolymerizable compositions sensitive to shorter wavelength (365 nm or 405 nm) light sources, and consequently the demand for photopolymerization initiators sensitive to such light sources has also increased.
Photopolymerization initiators are also called free radical photoinitiators. Upon exposure to light of a wavelength to which they are sensitive, they generate free radicals and thus initiate free radical polymerization of surrounding polymerizable compounds.
It is typically desired that such photoinitiators exhibit good sensitivity to light, especially in the UV region of the spectrum, low discoloration upon use, and good thermal stability (for storage and processing).
Some organic compounds comprising acyl and/or oxime ester groups are known as free radical photoinitiators. They have found use in color filter resists due to their absorption in the ultra-violet radiation region (between 300 and 450 nm). Irgacure OXE-01™ and OXE-02™ (available from BASF, Germany) are known photoinitiators for some applications, including color filter resists. Some triazine-based compounds are also known as useful photoinitiators.
The present description refers to a number of documents, the content of which is herein incorporated by reference in their entirety.